Chassis, generic

C05C4 Brake Pressure Sensor F Missing Calibration

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

The brake controller finds no stored calibration (offset or zero point) for pressure sensor F, the sixth hydraulic pressure sensor in its numbering. Which physical sensor carries the letter F is up to the maker, and none publishes C05C4. Comparable codes exist for sensors A and B: GM checks sensor B in its hybrid brake controller via test pulses after offset compensation, and Saab/GM calls for a scan-tool pressure sensor calibration after replacing the EBCM or the modulator. Hitachi learns pressure sensor zeros only while the master cylinder is pressureless and the pedal is released. A new module or hydraulic unit without the follow-up calibration is the usual cause. C05C5 to C05C8 cover the sensor's signal faults.

Likely causes

Calibration skipped after module or hydraulic unit replacement
Calibration interrupted by brake application or low voltage
Calibration data lost in the module memory

Symptoms

  • ABS, ESC or brake warning lamp on
  • Stability control or brake assist functions disabled

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–300
Time0.3–1 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

brake pressure sensor fbrake control module

Related codes

C05C5C0560C059BC059E

References: saabwisonline.com, patents.google.com, gsi.ext.gm.com.